Cornheads are harvesting heads mounted on the front of agricultural combines. Cornheads pull down adjacent rows of corn plants and snap the ears of corn of the plants.
To do this, the rows of corn plants must be guided into narrow gaps in row units that extend across the width of the cornhead. This guidance is provided by lightweight plastic dividers, also known as points and covers, the term “points” referring to the forward portion of the divider, and the term “covers” referring to the rear portion of the divider that covers most of the workings of the row units. These dividers are pointed on their forward ends and direct the corn plants either to the left or right, and directly into the crop-receiving gaps of each row unit.
These dividers not only guide the rows of corn plants into the proper openings in the row units, they also cover substantially the entire row unit to keep plant stalks and other materials from falling into and jamming the row units.
In order to maintain the row units, the operator must lift the dividers out of the way. The dividers are typically hinged about a laterally extending and horizontal axis at the rear of the dividers to pivot upward and uncover the row units.
In a first prior art design (FIG. 1) a stick is used to prop the dividers in a raised position. The stick extends upward and rearward from a cross-member attached to adjacent row units to a central portion of the row unit. There are drawbacks. This arrangement requires that the stick be stowed somewhere when the divider is lowered into its operating position. In addition, the operator is required to lift the divider by hand, with no assistance. Furthermore, the cross-member between adjacent row units prevents the operator from working on the sides of each row unit.
in another prior art design, a gas shock or extendible spring is used in place of the stick. This advantageously provided spring assistance to lift the cover. There are drawbacks: it still requires the cross-member. Furthermore, when the divider is in its lowered, operating position, the highly tensioned spring is compressed between the steel cross-member and the divider, commonly made of plastic. The spring presses on the plastic when the divider is closed, causing the plastic to tear and therefore the arrangement requires the addition of an additional strut or stiffener that extends from the center of the plastic divider where the spring is attached to the rear of the divider. In this way the load is better distributed over a larger surface area of the plastic divider.
In another prior art design rather than providing a cross-member fixed to and extending between adjacent row units at the front of the row units, the arrangement provides a forwardly extending beam that is cantilevered forward from a cross-member located at the rear of the row units. This forwardly extending beam supports the lower, forward end of a gas shock or spring. The upper end of the spring is attached to a tubular frame member that supports the plastic divider. This design contains the spring tension when dosed within the metal members and does not communicate it to the plastic. However it still requires a member extending forward into the gap between each pair of two adjacent row units. As in the previous example, the forward end of the compression spring is stationary and coupled to the frame.
What is needed, therefore, is a cornhead divider lift assist linkage in which the compression spring does not have a forward end that is stationary and fixed between the row units when the divider is raised. What is also needed is a cornhead divider lift assist linkage that does not apply significant pressure to the plastic divider when the divider is in its lowered operating position. It is an object of this invention to provide such a device in the independent claims of the present application. Further advantages are provided by each of the dependent claims.